When the speakers were finished I tested the impedance
(with crossover) as well as the frequency response of the full system,
the woofer (nearfield), and the port (nearfield). The woofer and
port nearfield responses will be somewhat inaccurate due to the
presence of the other woofer (and port) and tweeter - all in-ciruit.
Here's the impedance of the full system. Note how
easy it is to drive for a transistor amplifier (relatively high
impedance and resistive phase values).
Here's the port and nearfield response for a single
driver with the final port length (4.1").
Here's the calculated bass response of the system
by merging the port and nearfield response.
Here's the final frequency response measurement
with the response smoothed at 1/16 octave after splicing to the
nearfield (just to make it easier to read).
I've guessed at the relative level for the nearfield
test to ensure the results look good, but the next phase is a farfield
test to examine bass response. That really requires a bigger room
than I can test in.